Allow workspace_mount_path to use relative paths (#9615)

Co-authored-by: jianchuanli <jianchuanli@langcode.com>
Co-authored-by: Xingyao Wang <xingyao@all-hands.dev>

openhands/runtime/impl/docker/docker_runtime.py

@@ -261,7 +261,8 @@ class DockerRuntime(ActionExecutionClient):
             mount_mode = 'rw'  # Default mode
 
             # e.g. result would be: {"/home/user/openhands/workspace": {'bind': "/workspace", 'mode': 'rw'}}
-            volumes[self.config.workspace_mount_path] = {
+            # Add os.path.abspath() here so that relative paths can be used when workspace_mount_path is configured in config.toml
+            volumes[os.path.abspath(self.config.workspace_mount_path)] = {
                 'bind': self.config.workspace_mount_path_in_sandbox,
                 'mode': mount_mode,
             }